ES2316280A1 - Method and practical use system for measuring the imbalance power in electrical installations, and the device for calibration thereof - Google Patents

Abstract

Method and practical use system for measuring the imbalance potential of an electrical installation or system comprising: i) acquiring instantaneous values of voltage (v A , v B , v C ) and electrical intensity (i A , i B , i C ) of each of the phases A, B, C of the installation, and breaking them down into their fundamental frequency components (v A1 , v B1 , v C1 ), (i A1 , i B1 , i C1 ) ii) obtaining effective voltage and intensity values and angles for initial phase difference between voltage and intensity, and, starting from these effective values obtaining active powers (P A , P B , P C ) and reactive (Q A , Q B , Q C ) potentials for each of the phases iii) from the active and reactive potentials, obtaining (4) a phasor imbalance potentials ( A U ) according to the following expression: A 3/4 U = 2 p P A + a 2 P B + a P C + q 3/4 Q A + a 2 Q B + a Q C where a = 1 | 120 DEG and p and q are orthogonal unit phasors. The invention also relates to a device for calibrating (21) instruments for measurement instruments of this imbalance power.

Description

Procedure and implementation system for measuring the imbalance power in installations electrical, as well as the device for calibration.

Object of the invention

The present invention relates in a way General with measurement and calibration of measuring instruments of the phenomenon of imbalance in electrical installations, and more particularly with three-phase electrical systems at three and four  threads.

Background of the invention

Power is known in the technical literature of imbalance, magnitude that quantifies the effects of the phenomenon of the imbalance in electrical installations. They have developed different formulations for this potency of imbalance - according to different established theories of the electric power - which only give its magnitude, a real number. The imbalance power is not conservative, that is, not complies with the Principle of Energy Conservation and, therefore, the Unbalanced power of an electrical installation is not equal to the sum of the imbalance powers corresponding to each One of its integral elements. This limits and greatly hinders way its application to measure the effects of imbalances in industrial practice.

The imbalance power formulation in complex form it is unknown in the technical literature in the present moment This magnitude, which has been called "fasor imbalance power "by the authors of this invention, allows to determine the value of the imbalance power in any electrical installation knowing the imbalances of its integral parts. The system and measurement procedure that Claim allows to perform this function.

On the other hand, they are not known in practice Industrial calibrators of power measurement instruments imbalance formed by passive elements.

Description of the invention

The invention relates to a method and to a system for measuring the imbalance power in a electrical installation and a device for calibration, of according to claims 1, 2 and 6, respectively. Preferred embodiments of the procedure and system are defined in the dependent claims.

For this, it is established as a contribution fundamental the concept of "fasor imbalance power", magnitude whose module is the imbalance power and whose argument indicates the phase or phases in which the imbalance is greater, as well as if they affect more on the imbalance loads resistive or reactive. One of the properties, among others, of this new magnitude, which is not a real number but complex, is that the greatest imbalance power of a system or installation electric equals the sum of the power phasors of imbalance of each of the parts of the system or installation electrical, which considerably simplifies obtaining value of the total system imbalance power.

At present it is not known in the literature technique this magnitude "fasor imbalance power" and, by both, the equipment of measurement of the imbalance power both commercials such as those existing at the research level, cannot get the value of the imbalance power of the system to from each of its subsystems or integral parts.

The present invention provides a procedure and system for measuring imbalance power of an electrical system or installation, magnitude that is expressed as a complex number, with module and argument, thereby exceeding limitations mentioned above. The formulation in form complex imbalance power makes it possible for the fasor total imbalance power of an installation or system electric equals the sum of the power phasors of imbalance of each of its elements; so it is possible to obtain the value and effects of imbalances in a part of a electrical installation from the imbalance values in each of its components.

According to a first aspect of the invention, this refers to a phasor measurement procedure unbalanced power of an installation or electrical system which includes:

i)

acquire instant values of voltage (V_ {A}, V_ {B}, V_ {C}) and intensity (i_ {A}, i_ {B}, i_ {C}) of each of the phases A, B, C of the installation or electrical system, and break them down into their components frequently fundamental (V_ {A1}, V_ {B1}, v_ {C1}), (i_ {A1}, i_ {B1}, i_ {C1});

ii)

obtain effective tension values e intensity and angles of initial offset between voltage and intensity, and from these effective values obtain active powers (P_ {A}, P_ {{}}}, P_ {C}) and reagents (Q_ {A}, Q_ {B}, Q_ {C}) for each of the phases;

iii)

to from the active and reactive powers, a phasor is obtained unbalance power (\ overline {A} U), according to the following expression:

100

where a = 1_ {| \ 120 o, and \ overline {p} and \ overline {q} are unit phasors orthogonal

According to a possible realization of procedure of the invention, in step ii) values are obtained effective voltage (V_ {A1}, V_ {B1}, V_ {C1}) and intensity (I_ {A1}, I_ {B1}, I_ {C1}) and offset angles (\ varphi_ {A1}, \ varphi_ {B1}, \ varphi_ {C1}) between voltage and intensity for the fundamental frequency; and the active powers (P_ {A}, P_ {B}, P_ {C}) and reagents (Q_ {A}, Q_ {B}, Q_ {C}) for each of The phases are calculated according to the following expression:

101

Alternatively, in step ii) they are obtained effective values of positive sequence voltage and frequency fundamental (V_ {A1 +}, V_ {B1 +}, V_ {C1 +}) and offset angles (\ varphi_ {A1 +}, \ varphi_ {B1 +} \ varphi_ {C1 +}) between voltage e intensity for the fundamental frequency (I_ {A1}, I_ {B1}, I_ {C1}); the active powers (P_ {A}, P_ {B}, P_ {C}) and reagents (Q_ {A}, Q_ {B}, Q_ {C}) for each of the phases are They calculate according to the following expression:

102

According to a second aspect of the invention, this refers to a system for measuring the power of imbalance of an installation or electrical system, which understands:

-

a acquisition module configured to acquire instantaneous values of voltage (V_ {A}, V_ {B}, V_ {C}) and intensity (i_ {A}, i_ {B}, i_ {C}) for each of the phases A, B, C of said electrical installation;

-

a analysis module configured to obtain effective values of voltage (V_ {A1}, V_ {B1}, V_ {C1}) and intensity (I_ {A1}, I_ {B1}, I_ {C1}) and offset angles (\ varphi_ {A1}, \ varphi_ {B1}, \ varphi_ {C1}) between voltage and intensity for the fundamental frequency;

-

a active and reactive power module configured to obtain active powers (P_ {A}, P_ {{}}}, P_ {C}) and reactive (Q_ {A}, Q_ {B}, Q_ {C}) for each of the phases;

-

a fasor module configured to obtain a complex number in form polar or binomial or fasor imbalance power \ overline {A} U, from the values of active powers and reagents according to the following expression:

103

where a = 1_ {| \ 120 o, and \ overline {p} and \ overline {q} are unit phasors orthogonal

According to a preferred embodiment the active and reactive powers module calculates those powers of I agree with the following expression:

104

       \ newpage
    

According to another possible embodiment, the system also includes a symmetric module configured to obtain values effective positive sequence voltage and fundamental frequency (V_ {A1 +}, V_ {B1 +}, V_ {C1 +}) and offset angles (\ varphi_ {A1 +}, \ varphi_ {B1 +}, \ varphi_ {C1 +}) between voltage e intensity for the fundamental frequency; and in such because the module of active and reactive powers calculate these according to the following expression:

105

The system also preferably includes a display module configured to represent one or more quantities obtained in or used by the different modules that make up the system.

According to another aspect of the invention, This refers to an instrument calibrating device measurement of the imbalance power of an installation or system electric, comprising:

-

a three-phase stabilized, balanced and sinusoidal, responsible for supplying the corresponding energies to inefficiency due to imbalance; Y

-

to the minus an imbalance pattern circuit consisting of elements liabilities, coils and capacitors or their equivalents formed by electronic converters, the values of said elements being Passive function of the phasor power imbalance module \ overline {A} U, calculating this as indicated in previous.

The pattern circuit or power of imbalance absorb imbalance currents, calibrated at a preset value.

These calibrating devices provide simplicity, economy and physical foundation tailored to the power of imbalance against other possible electronic calibrators, commercialized or not, less suitable for industrial environments.

Brief description of the drawings

To complement the description that is being performing and in order to help a better understanding of the characteristics of the invention, according to examples preferred for practical realization of it, is accompanied as integral part of said description of a set of drawings in where, for illustrative and non-limiting purposes, it has been represented the next:

Figure 1 is a diagram showing the Operational sequence of the process of the invention.

Figure 2 is a diagram representing a possible realization of the device for measuring the phasor imbalance power of the invention.

Figure 3 is a diagram representing a possible structure of the power gauge imbalance.

Figure 4 is a diagram representing a possible procedure for obtaining the power phasor of imbalance.

Figure 5 is a diagram representing a possible alternative procedure for the determination of the phasor imbalance power.

Figure 6 is a diagram showing the constitution of the pattern for the power gauge of imbalance.

Description of a preferred embodiment of the invention

As shown in Figure 1, a possible Performing the procedure for measuring the phasor power of imbalance in an electrical installation, object of the present invention, comprises the following operations:

-

Digital signal processing 1 sampled obtained by physical system 6 (see figure 2) of measurement and acquisition of electrical signals from the device, obtaining the matrices of effective values and initial phases of voltage and intensity at fundamental frequency for each phase, in total six matrices for each phase of tension e intensity.

-

With these matrices are obtained (in 3) effective value matrices and initial phases for positive sequence components with a matrix for positive sequence voltages.

-

TO from the effective value matrices and initial phases of voltage and intensity for the fundamental frequency, are obtained the active and reactive powers for each of the phases (in 2).

-

TO from the active and reactive powers the fasor is obtained imbalance power (in 4), according to the expression (1) indicated later.

-

The graphic and numerical information of the phasor imbalance power, as well as certain values of the physical quantities used during the procedure, they are displayed (in 5) on a device display.

The device for the implementation of the measurement procedure, as shown in figure 2, is formed by a physical system 6 for measurement and signal acquisition electrical -hardware- and a power measurement program 7 electric

The physical system 6 consists of sensors 8 measuring voltage and intensity, which measure their values snapshots; of signal conditioners 9 that adapt the Secondary current of each sensor at the voltage applicable to the  analog inputs of the acquisition card; of such a card acquisition 10 or equivalent device that converts signals analog voltage and intensity in a series of samples discrete that are used as input in the measurement program; from a processor system 11 with a motherboard on which the acquisition card 10 so that they can exchange discrete samples of the voltage and intensity signals with the measurement program 7; and of a 12 touch LCD screen or device of display in which all information about the waveforms and the value of all electrical quantities Related to the phasor power imbalance measurement: voltages, intensities, active and reactive powers, components symmetrical, fasor power imbalance power.

Measurement Program 7 consists of following modules:

- Acquisition module 13 that acquires samples of voltage and intensity, and saves them in a vector for each of they.

- Analysis module 14 that obtains the matrices of tensions and intensities in effective value and in phase for the fundamental frequency, from the samples acquired in the previous module; In addition, the numerical integration is obtained effective values of all tensions and intensities of each of the phases.

- Symmetric module 16 that obtains the matrices of the positive sequence components, in effective value and in phase of the tensions for the fundamental frequency, from of the matrices obtained in the previous module.

- Module of active and reactive powers 15 responsible for obtaining the values of the active powers and reagents for each type of installation topology electric

- Fasor 17 imbalance power module responsible for obtaining the value of the power phasor of imbalance.

A typical application that illustrates what previously commented is, among others, the process of obtaining of the greatest power of imbalance in one of the centers of transformation of a population or a factory.

Figure 4 schematically shows a possible calculation process of the aforementioned magnitude. Instantaneous values of voltages (V_ {A}, V_ {B}, V_ {C}) and currents (i_ {A}, i_ {B}, i_ {C}) of the different phases are registered and broken down into its fundamental frequency components (V_ {A1}, V_ {B1}, V_ {C1}) (i_ {A1}, i_ {B1}, i_ {C1}), 50/60 Hz, and in its harmonic components. Then it obtain effective values and offset angles of fundamental frequency phase voltages and currents (V_ {A1}, V_ {B1}, V_ {C1}) (I_ {A1}, I_ {B1}, I_ {C1}) (\ varphi_ {A1}, \ varphi_ {B1}, \ varphi_ {C1}). With these values, the active powers (P_ {A}, P_ {{}}}, P_ {C}) and reactive (Q_ {A}, Q_ {B}, Q_ {C}) of each phase according to the following expressions:

106

Finally, the active power values and reactive of each phase are substituted in the following expression of fasor imbalance power (\ overline {A} U):

107

expression that is original, and in the which a = 1_ {| \ 120 ^ {o}}, and \ overline {p} and \ overline {q} are unit phasors orthogonal

As shown schematically in Figure 5, another alternative procedure to get with very good approximation of the phasor power imbalance value, consists in calculating the active and reactive powers of each phase from of the symmetric components of the phase voltages, of fundamental frequency As in the previous case, the instantaneous stress values (V_ {A}, V_ {B}, V_ {C}) and currents (i_ {A}, i_ {B}, i_ {C}) of the different phases are registered and broken down into its frequency components fundamental (V_ {A1}, V_ {B1}, V_ {C1}) (i_ {A1}, i_ {B1}, i_ {C1}), 50/60 Hz, and in its harmonic components. Applying the expressions of the Stokvis-Fortescue Theorem are obtain the effective values of the sequence tensions positive and fundamental frequency (V_ {A1 +}, V_ {B1 +}, V_ {C1 +}) and offset angles (\ varphi_ {A1 +}, \ varphi_ {B1 +}, \ varphi_ {C1 +}) of these voltages with the frequency currents fundamental; and from these the active powers are obtained (P_ {A}, P_ {{}}}, P_ {C}) and reagents (Q_ {A}, Q_ {B}, Q_ {C}) according to the following expressions:

108

for subsequent replacement in the expression [1) of the phasor power of imbalance.

Finally, measurement program 7 includes a display module 18, responsible for representing on screen graphic and numerical information of the phasor imbalance power, as well as the values of physical quantities, such as: values effective tensions and intensities; active powers and reagents for each phase; frequency symmetric components fundamental.

Figure 3 shows a possible embodiment of the 21 gauge of power measuring instruments imbalance. It is formed by a power supply three-phase 19 and by standard measurement circuits of the power of imbalance 20.

The three-phase power supply 19 is the device responsible for supplying the corresponding energies to inefficiency due to imbalance. It is a power supply three-phase, stabilized, 50/60 Hz frequency.

The pattern circuits of the power of imbalance 20 are passive devices, formed by coils and capacitors, or their equivalent formed by circuits electronic, which absorb the currents and powers of imbalance, calibrated to a preset value. A configuration preference of a standard circuit of the imbalance power 20 shown in figure 6 and possible values of the elements constituents thereof are indicated below:

109

where Au is the power of imbalance.

The invention has been described according to preferred embodiments thereof, but for the expert in the matter will be apparent that multiple variations can be introduced into said preferred embodiments without exceeding the object of the claimed invention.

Claims (8)

         \ global \ parskip0.950000 \ baselineskip
      

1. Procedure for measuring the power of imbalance of an installation or electrical system, which understands:

i)

acquire instant values of voltage (V_ {A}, V_ {B}, V_ {C}) and intensity (i_ {A}, i_ {B}, i_ {C}) of each of the phases A, B, C of the installation or electrical system, and break them down into their components frequently fundamental (V_ {A1}, V_ {B1}, V_ {C1}), (i_ {A1}, i_ {B1}, i_ {C1});

ii)

obtain effective stress values (V_ {A1}, V_ {B1}, V_ {C1}) and intensity (I_ {A1}, I_ {B1}, I_ {C1}) and offset angles (\ varphi_ {A1}, \ varphi_ {B1}, \ varphi_ {C1}) initial between voltage and intensity for the fundamental frequency;

iii)

to from these effective values for the fundamental frequency obtained in the previous step, obtain active powers (P_ {A}, P_ {B}, P_ {C}) and reagents (Q_ {A}, Q_ {B}, Q_ {C}) for each one of the phases; Y

iv)

to from the active and reactive powers, a fasor (4) is obtained unbalance power (\ overline {A} U), according to the following expression:

110 where a = 1_ {| \ 120 o, and \ overline {p} and \ overline {q} are unit phasors orthogonal 2. Method according to claim 1, characterized in that the active (P_, P_, P C) and reactive (Q_ {A}, Q_ {B}, Q_ {C}) powers for each of the phases are obtained according to the following expression: 111 3. Method according to claim 1, characterized in that from said effective values for the fundamental frequency, effective values of positive sequence voltage and fundamental frequency (V_ {+1}, V_ {B1 +}, V_ {C1 +}) and angles are obtained phase shift (\ varphi_ {A1 +}, \ varphi_ {B1 +}, \ varphi_ {C1 +}) between voltage and intensity for the fundamental frequency, and the active powers (P_ {A}, P_ {B}, P_ {C}) and reagents (Q_ {A}, Q_ {B}, Q_ {C}) for each of the phases are obtained according to the following expression: 112 4. A system for measuring the power of imbalance of an installation or electrical system, which understands:

-

a acquisition module (13) configured to acquire values instantaneous voltage (V_ {A}, V_ {B}, V_ {C}) and intensity (i_ {A}, i_ {B}, i_ {C}) for each of the phases A, B, C of said electrical installation;

-

a analysis module (14) configured to obtain effective values of voltage (V_ {A1}, V_ {B1}, V_ {C1}) and intensity (I_ {A1}, I_ {B1}, I_ {C1}) and offset angles (\ varphi_ {A1}, \ varphi_ {B1}, \ varphi_ {C1}) between voltage and intensity for the fundamental frequency;

-

a active and reactive power module (15) configured to obtain active (P_, P_, P_) and reactive powers (Q_ {A}, Q_ {B}, Q_ {C}) for each of the phases;

-

a fasor module (17) configured to obtain a complex number in polar form or binomial form or fasor imbalance power (\ overline {A} U), from the values of active powers and reagents according to the following expression:

113 where a = 1_ {| \ 120 o, and \ overline {p} and \ overline {q} are unit phasors orthogonal

         \ global \ parskip1.000000 \ baselineskip
      

5. System according to claim 4, characterized in that the module of active and reactive powers (15) calculates them according to the following expression: 114 System according to claim 4, characterized in that it also includes a symmetric module (16) configured to obtain effective values of positive sequence voltage and fundamental frequency (V_ {A1 +}, V_ {B1 +}, V_ {C1 +}) and angles phase shift (\ varphi_ {A1 +}, \ varphi_ {B1 +}, \ varphi_ {C1 +}) between voltage and intensity for the fundamental frequency (I_ {A1}, I_ {B1}, I_ {C1}); and because the module of active powers and reagents (15) calculate them according to the following expression: 115 7. System according to any of claims 4-6, characterized in that it also includes a display module (18), configured to represent one or more quantities obtained in, or used by, the different modules that make up the system. 8. Instrument calibrator device (21) for measuring the imbalance power of an installation or electrical system, comprising:

-

a three-phase power supply (19) stabilized, balanced and sinusoidal; Y

-

to the minus an imbalance pattern (20) formed by passive elements,  coils (L_ {ip}, L_ {hp}) and capacitors (C_ {ip}, C_ {hp}) or their equivalents formed by electronic converters, being the values of said passive elements function of the phasor module imbalance power \ overline {A} _ {U}, this being calculated as indicated in any of the claims precedents